Double talk detector
First Claim
1. A method of detecting that a received coded speech signal is dominated by a non-echo signal, comprising the steps of:
- if the signal power of a received speech signal exceeds a first threshold value, then extracting the Line Spectral Pairs (LSPs) from a coded speech frame of said received speech signal;
converting each of said extracted LSPs into Line Spectral Frequencies (LSFs), ω
i, and calculating the distance between each two adjacent LSFs; and
,for each of said distances that is smaller than a second threshold value, calculating the frequency of the spectral peak, ω
c, surrounded by said LSFs, and determining whether said spectral peak is an echo.
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Accused Products
Abstract
A double talk detector for controlling the echo path estimation in a telecommunication system by indicating when a received coded speech signal is dominated by a non-echo signal; i.e., that so-called double talk exists. This is determined by extracting LSPs from a coded speech frame of the received coded speech signal when the signal power exceeds a first threshold value, converting each of said extracted LSPs into LSFs, and calculating the distance between each two adjacent LSFs. For each distance that is smaller than a second threshold, a spectral peak is located between the two LSFs, and it is determined whether said spectral peak is an echo or not. When a predetermined number of non-echo spectral peaks are located in the received speech signal, double talk will be indicated, and the echo path estimation may be disabled.
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Citations
28 Claims
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1. A method of detecting that a received coded speech signal is dominated by a non-echo signal, comprising the steps of:
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if the signal power of a received speech signal exceeds a first threshold value, then extracting the Line Spectral Pairs (LSPs) from a coded speech frame of said received speech signal; converting each of said extracted LSPs into Line Spectral Frequencies (LSFs), ω
i, and calculating the distance between each two adjacent LSFs; and
,for each of said distances that is smaller than a second threshold value, calculating the frequency of the spectral peak, ω
c, surrounded by said LSFs, and determining whether said spectral peak is an echo. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of estimating the echo path in a telecommunication system, wherein the echo path estimation is deactivated when a received coded speech signal is dominated by a non-echo-signal, the method comprising the steps of:
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if the signal power of a received speech signal exceeds a first threshold value, then extracting the Line Spectral Pairs (LSPs) from a coded speech frame of said received speech signal; converting each of said extracted LSPs into a corresponding Line Spectral Frequency (LSF), ω
i, and calculating the distance between each two adjacent LSFs;for each distance that is smaller than a second threshold value, calculating the frequency of the spectral peak, ω
c, surrounded by said LSF, and determining whether said spectral peak is an echo; and
,deactivating the echo path estimation when a predetermined number of spectral non-echo peaks are located. - View Dependent Claims (11, 12, 13)
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14. A double talk detector arranged to be connected to a coded received speech signal and to a coded transmitted first speech signal in a telecommunication system for determining when said received speech signal is dominated by a non-echo signal, the double talk detector comprising:
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a signal power monitor arranged to determine when the signal power of a received speech signal exceeds a first threshold value; a spectral peak locator arranged to; extract the LSPs from a coded speech frame of the received speech signal and to convert each of said extracted LSPs into a corresponding LSF; and
,calculate the distance between each two adjacent LSFs, and calculate a spectral peak, ω
c, surrounded by two LSFs separated by a distance that is smaller than a second threshold value; and
,an echo locator arranged to determine whether a located spectral peak is an echo. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. An echo path estimating device for a telecommunication system, arranged to deactivate the estimation of an echo path dominated by a non-echo-signal, the echo path estimating device comprising:
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a double talk detector arranged to be connected to a coded received speech signal and to a coded transmitted first speech signal in said telecommunication system, said double talk detector comprising; a signal power monitor arranged to determine when the signal power of a received speech signal exceeds a first threshold value; a spectral peak locator arranged to; extract Line Spectral Pairs (LSPs) from a coded speech frame of the received speech signal and to convert each of said extracted LSPs into a corresponding Line Spectral Frequency (LSF), ω
i;calculate the distance between each two adjacent LSFs, and calculate a spectral peak, ω
c, surrounded by two LSFs separated by a distance that is smaller than a second threshold value; and
,an echo locator arranged to determine whether a located spectral peak is an echo. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification